Synthesis, Characterization and Thermal Study of Divalent Germanium, Tin and Lead Triazenides for Atomic Layer Deposition

The number of M–N bonded divalent group 14 precursors suitable for atomic layer deposition is limited, in particular for Ge and Pb. A majority of the reported precursors are dicoordinated, with the only tetracoordinated example being the Sn(II) amidinate. No such Ge(II) and Pb(II) compounds have been demonstrated. Herein, we present tetracoordinated Ge(II), Sn(II) and Pb(II) complexes bearing two sets of the bidentate 1,3-di-tert-butyl triazenide ligands. These compounds are highly volatile and show ideal behavior by thermogravimetric analysis. However, they have unusual thermal properties and exhibit instability during sublimation. Interestingly, the instability is not only temperature dependent but also facilitated by reduced pressure. Using quantum-chemical density functional theory, a gas-phase decomposition pathway was mapped out. The pathway account for the unusual thermal behavior of the compounds and is supported by electron impact mass spectrometry data.

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Synthesis and Thermal Study of Hexacoordinated Aluminum(III) Triazenides for Use in Atomic Layer Deposition

10.26434/chemrxiv.13299299.v1 ◽

2020 ◽

Author(s):

Rouzbeh Samii ◽

David Zanders ◽

Sydney Buttera ◽

Vadim Kessler ◽

Lars Ojamäe ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Density Functional ◽

Atomic Layer ◽

Single Step ◽

Vapor Pressures ◽

Scanning Calorimetry ◽

Layer Deposition ◽

Ligand Interactions ◽

Deposition Processes ◽

Decomposition Pathway

Amidinate and guanidinate ligands have been used extensively to produce volatile and thermally stable precursors for atomic layer deposition. The triazenide ligand is relatively unexplored as an alternative ligand system. Herein, we present six new Al(III) complexes bearing three sets of a 1,3-dialkyltriazenide ligand. These complexes volatilize quantitatively in a single step with onset volatilization temperatures of ~150 °C and 1 Torr vapor pressures of ~134 °C. Differential scanning calorimetry revealed these Al(III) complexes exhibited exothermic events that overlapped with the temperatures of their mass loss events in thermogravimetric analysis. Using quantum chemical density functional theory computations, we found a decomposition pathway transforming the relatively large hexacoordinated Al(III) precursor into a smaller dicoordinated complex. The pathway relies on previously unexplored inter-ligand interactions, in which protons migrate between the triazenide ligands. These new Al(III) triazenides provides a series of alternative precursors with unique thermal properties that could be highly advantageous for vapor deposition processes of Al containing materials.

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Synthesis and Thermal Study of Hexacoordinated Aluminum(III) Triazenides for Use in Atomic Layer Deposition

10.26434/chemrxiv.13299299 ◽

2020 ◽

Author(s):

Rouzbeh Samii ◽

David Zanders ◽

Sydney Buttera ◽

Vadim Kessler ◽

Lars Ojamäe ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Density Functional ◽

Atomic Layer ◽

Single Step ◽

Vapor Pressures ◽

Scanning Calorimetry ◽

Layer Deposition ◽

Ligand Interactions ◽

Deposition Processes ◽

Decomposition Pathway

Amidinate and guanidinate ligands have been used extensively to produce volatile and thermally stable precursors for atomic layer deposition. The triazenide ligand is relatively unexplored as an alternative ligand system. Herein, we present six new Al(III) complexes bearing three sets of a 1,3-dialkyltriazenide ligand. These complexes volatilize quantitatively in a single step with onset volatilization temperatures of ~150 °C and 1 Torr vapor pressures of ~134 °C. Differential scanning calorimetry revealed these Al(III) complexes exhibited exothermic events that overlapped with the temperatures of their mass loss events in thermogravimetric analysis. Using quantum chemical density functional theory computations, we found a decomposition pathway transforming the relatively large hexacoordinated Al(III) precursor into a smaller dicoordinated complex. The pathway relies on previously unexplored inter-ligand interactions, in which protons migrate between the triazenide ligands. These new Al(III) triazenides provides a series of alternative precursors with unique thermal properties that could be highly advantageous for vapor deposition processes of Al containing materials.

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Composite Nanostructures of TiO2and ZnO for Water Splitting Application: Atomic Layer Deposition Growth and Density Functional Theory Investigation

Advanced Functional Materials ◽

10.1002/adfm.201505524 ◽

2016 ◽

Vol 26 (27) ◽

pp. 4882-4889 ◽

Cited By ~ 30

Author(s):

Marina Kulmas ◽

Leanne Paterson ◽

Katja Höflich ◽

Muhammad Y. Bashouti ◽

Yanlin Wu ◽

...

Keyword(s):

Density Functional Theory ◽

Atomic Layer Deposition ◽

Water Splitting ◽

Density Functional ◽

Atomic Layer ◽

Functional Theory ◽

Composite Nanostructures ◽

Layer Deposition

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Density functional theory investigation on formation of nanoscale PbS materials and its fabrication in silica optical fiber via atomic layer deposition

Optical Fiber Technology ◽

10.1016/j.yofte.2020.102257 ◽

2020 ◽

Vol 58 ◽

pp. 102257

Author(s):

Yanhua Dong ◽

Caiyun Su ◽

Xiangping Pan ◽

Yangyang Zhao ◽

Jianxiang Wen ◽

...

Keyword(s):

Density Functional Theory ◽

Atomic Layer Deposition ◽

Optical Fiber ◽

Density Functional ◽

Atomic Layer ◽

Functional Theory ◽

Layer Deposition ◽

Silica Optical Fiber

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Initial surface reactions in atomic layer deposition of HfSixOy and HfO2: A comparative study by density functional theory

Thin Solid Films ◽

10.1016/j.tsf.2007.10.107 ◽

2008 ◽

Vol 516 (10) ◽

pp. 2966-2972 ◽

Cited By ~ 6

Author(s):

Jie Ren ◽

Yongqi Hu ◽

Jianying Wang ◽

Haichao Jiang ◽

David Wei Zhang

Keyword(s):

Density Functional Theory ◽

Atomic Layer Deposition ◽

Comparative Study ◽

Density Functional ◽

Surface Reactions ◽

Atomic Layer ◽

Initial Surface ◽

Functional Theory ◽

Layer Deposition

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First Principles Mechanistic Study of Self-Limiting Oxidative Adsorption of Remote Oxygen Plasma During the Atomic Layer Deposition of Alumina

10.26434/chemrxiv.6377372 ◽

2018 ◽

Author(s):

Glen N. Fomengia ◽

Michael Nolan ◽

Simon D. Elliott

Keyword(s):

Atomic Layer Deposition ◽

First Principles ◽

Density Functional ◽

Atomic Layer ◽

Molecular Water ◽

Mechanistic Study ◽

Hydroxyl Groups ◽

Layer Deposition ◽

Surface Intermediates ◽

By Products

Plasma-enhanced atomic layer deposition (ALD) of metal oxides is a rapidly gaining interest especially in the electronics industry because of its numerous advantages over the thermal process. However, the underlying reaction mechanism is not sufficiently understood, particularly regarding saturation of the reaction and densification of the film. In this work, we employ first principles density functional theory (DFT) to determine the predominant reaction pathways, surface intermediates and by-products formed when constituents of O2-plasma or O3 adsorb onto a methylated surface typical of TMA-based alumina ALD. The main outcomes are that a wide variety of barrierless and highly exothermic reactions can take place. This leads to the spontaneous production of various by-products with low desorption energies and also of surface intermediates from the incomplete combustion of –CH3 ligands. Surface hydroxyl groups are the most frequently observed intermediate and are formed as a consequence of the conservation of atoms and charge when methyl ligands are initially oxidized (rather than from subsequent re-adsorption of molecular water). Anionic intermediates such as formates are also commonly observed at the surface in the simulations. Formaldehyde, CH2O, is the most frequently observed gaseous by-product. Desorption of this by-product leads to saturation of the redox reaction at the level of two singlet oxygen atoms per CH3 group, where the oxidation state of C is zero, rather than further reaction with oxygen to higher oxidation states. We conclude that the self-limiting chemistry that defines ALD comes about in this case through the desorption by-products with partially-oxidised carbon. The simulations also show that densification occurs when ligands are removed or oxidised to intermediates, indicating that there may be an inverse relationship between Al/O coordination numbers in the final film and the concentration of chemically-bound ligands or intermediate fragments covering the surface during each ALD pulse. Therefore reactions that generate a bare surface Al will produce denser films in metal oxide ALD.

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Atomic Layer Deposition of CeOx Nanoclusters on TiO2

10.26434/chemrxiv.12320855 ◽

2020 ◽

Author(s):

Ji Liu ◽

Saeed Saedy ◽

Rakshita Verma ◽

J. Ruud van Ommen ◽

Michael Nolan

Keyword(s):

Atomic Layer Deposition ◽

Band Gap ◽

Cerium Oxide ◽

Growth Rates ◽

Density Functional ◽

Visible Region ◽

Atomic Layer ◽

Hydroxyl Groups ◽

Powder Materials ◽

Layer Deposition

Titanium dioxide has a band-gap in the ultra violet region and there have been many efforts to shift light absorption to the visible region. In this regard, surface modification with metal oxide clusters has been used to promote band-gap reduction. CeOx-modified TiO2 materials have exhibited enhanced catalytic activity in water gas shift, but the deposition process used is not well-understood or suitable for powder materials. Atomic layer deposition (ALD) has been used for deposition of cerium oxide on TiO2. The experimentally reported growth rates using typical Ce metal precursors such as β-diketonates and cyclopentadienyls are low, with reported growth rates of ca. 0.2-0.4 Å/cycle. In this paper, we have performed density functional theory calculations to reveal the reaction mechanism of the metal precursor pulse together with experimental studies of ALD of CeOx using two Ce precursors, Ce(TMHD)4 and Ce(MeCp)3. The nature and stability of hydroxyl groups on anatase and rutile TiO2 surfaces are determined and used as starting substrates. Adsorption of the cerium precursors on the hydroxylated TiO2 surfaces reduces the coverage of surface hydroxyls. Computed activation barriers for ligand elimination in Ce(MeCp)3 indicate that ligand elimination is not possible on anatase (101) and rutile (100) surface, but it is possible on anatase (001) and rutile (110). The ligand elimination in Ce(TMHD)4 is via breaking the Ce-O bond and hydrogen transfer from hydroxyl groups. For this precursor, the ligand elimination on the majority surface facets of anatase and rutile TiO2 are endothermic and not favourable. It is difficult to deposit Ce atom onto hydroxylated TiO2 surface using Ce(TMHD)4 as precursor. Attempts for deposit cerium oxide on TiO2 nanoparticles that expose the anatase (101) surface show at best a low deposition rate and this can be explained by the non-favorable ligand elimination reactions at this surface.

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Tuning the properties of metal–organic framework nodes as supports of single-site iridium catalysts: node modification by atomic layer deposition of aluminium

Faraday Discussions ◽

10.1039/c7fd00031f ◽

2017 ◽

Vol 201 ◽

pp. 195-206 ◽

Cited By ~ 20

Author(s):

Dong Yang ◽

Mohammad R. Momeni ◽

Hakan Demir ◽

Dale R. Pahls ◽

Martino Rimoldi ◽

...

Keyword(s):

Atomic Layer Deposition ◽

Density Functional ◽

Metal Organic Framework ◽

Density Functional Theory Calculations ◽

Atomic Layer ◽

Single Site ◽

Iridium Complexes ◽

Layer Deposition ◽

Metal Organic ◽

Organic Framework

The metal–organic framework NU-1000, with Zr6-oxo, hydroxo, and aqua nodes, was modified by incorporation of hydroxylated Al(iii) ions by ALD-like chemistry with [Al(CH3)2(iso-propoxide)]2 followed by steam (ALD = atomic layer deposition). Al ions were installed to the extent of approximately 7 per node. Single-site iridium diethylene complexes were anchored to the nodes of the modified and unmodified MOFs by reaction with Ir(C2H4)2(acac) (acac = acetylacetonate) and converted to Ir(CO)2 complexes by treatment with CO. Infrared spectra of these supported complexes show that incorporation of Al weakened the electron donor tendency of the MOF. Correspondingly, the catalytic activity of the initial supported iridium complexes for ethylene hydrogenation increased, as did the selectivity for ethylene dimerization. The results of density functional theory calculations with a simplified model of the nodes incorporating Al(iii) ions are in qualitative agreement with some catalyst performance data.

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The Competitive Reactions in Atomic Layer Deposition of HfO2, ZrO2 and Al2O3 on Hydroxylated Si(100) Surfaces: A Density Functional Theory Study

Materials Science Forum ◽

10.4028/www.scientific.net/msf.675-677.1249 ◽

2011 ◽

Vol 675-677 ◽

pp. 1249-1252

Author(s):

Jie Ren ◽

Guang Fen Zhou

Keyword(s):

Density Functional Theory ◽

Atomic Layer Deposition ◽

Density Functional ◽

Surface Reactions ◽

Atomic Layer ◽

Density Functional Theory Study ◽

Geometrical Structures ◽

Functional Theory ◽

Competitive Reactions ◽

Layer Deposition

The competitive reactions in atomic layer deposition (ALD) of HfO2, ZrO2 and Al2O3 on the hydroxylated Si(100) surfaces are investigated by using density functional theory. The surface reactions in ALD of HfO2 and ZrO2 show large similarities in energetics and geometrical structures. However, both of them show discrepancies with the surface reactions in ALD of Al2O3. In addition, by comparing with the self-termination reactions, we could find that the further growth reactions are both kinetically and thermodynamically more favorable in ALD of HfO2, ZrO2 and Al2O3.

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